Alert archive / Nebraska / Mesoscale Discussions in 2004

Mesoscale Discussion 412

April 21, 20046 counties in Iowa; 20 counties in Nebraska; 19 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2004, 3:04 PM CDT for 6 counties in Iowa; 20 counties in Nebraska; 19 counties in South Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 21, 2004, 3:04 PM CDT (20:04 UTC)
Expired: Apr 21, 2004, 5:30 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 45 counties

Harrison County, IA, Lyon County, IA, Monona County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Antelope County, NE, Boyd County, NE, Brown County, NE, Burt County, NE, Cedar County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Garfield County, NE, Holt County, NE, Keya Paha County, NE, Knox County, NE, Loup County, NE, Madison County, NE, Pierce County, NE, Rock County, NE, Stanton County, NE, Thurston County, NE, Wayne County, NE, Wheeler County, NE, Aurora County, SD, Bon Homme County, SD, Charles Mix County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Hanson County, SD, Hutchinson County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Sanborn County, SD, Tripp County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 8.1 hours before the alert went out and 215 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 842 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: -92 m²/s²
0-3 km storm-relative helicity: -12 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

405 
ACUS11 KWNS 212005
SWOMCD
SPC MCD 212004 
IAZ000-NEZ000-MNZ000-SDZ000-212230-

MESOSCALE DISCUSSION 0412
NWS STORM PREDICTION CENTER NORMAN OK
0304 PM CDT WED APR 21 2004

AREAS AFFECTED...S-CENTRAL/SERN SD...NWRN IA...AND N-CENTRAL AND
NERN NEB

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 212004Z - 212230Z

SCATTERED THUNDERSTORMS ACROSS N-CENTRAL/NERN NEB...S-CENTRAL/SERN
SD...AND NWRN IA WILL BE ASSOCIATED WITH THE THREAT OF MARGINALLY
SEVERE HAIL THROUGH LATE THIS EVENING. 

AT 20Z...SCATTERED THUNDERSTORMS HAVE DEVELOPED IN STEEP LOW-MID
LEVEL LAPSE RATE ENVIRONMENT ACROSS THE DISCUSSION AREA. WITH
SURFACE TEMPERATURES IN THE UPPER 50S TO LOW 60S...SBCAPE VALUES ARE
MARGINAL...RANGING FROM 500-1000 J/KG IN A SSE-NNW AXIS FROM SWRN IA
TO ERN SD. ALTHOUGH STORMS WILL LIKELY NOT ORGANIZE ON THE
MESOSCALE...PRESENCE OF MARGINAL INSTABILITY...STEEP LAPSE
RATES...AND SFC-6KM SHEAR AROUND 30 KT SUGGESTS STRONGER CORES COULD
CONTAIN SEVERE HAIL. LOW WBZ HEIGHTS AND COLD MID-LEVEL TEMPERATURES
/ -24C AT 500MB / WILL CONTRIBUTE TO HAIL POTENTIAL. HAIL THREAT
SHOULD DECREASE BY LATE EVENING COINCIDENT WITH BOUNDARY LAYER
STABILIZATION AND WEAKENING OF CONVECTIVE UPDRAFTS.

..BANACOS.. 04/21/2004

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...FSD...OAX...ABR...LBF...UNR...

44349767 44269721 43529634 43019577 41939535 41659585
41719686 41829874 41950005 42680077 43280022 43619909

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 20, 7:20 PM CDT	Mesoscale Discussion	SPC	Appanoose, Clarke, Dallas, Davis, Decatur, Henry and 19 more	115 min
Apr 20, 8:06 PM CDT	Mesoscale Discussion	SPC	Fremont, Harrison, Mills, Monona, Montgomery, Page and 2 more	84 min

Nearby

Mesoscale Discussions in Nebraska, 2004 Mesoscale Discussions in South Dakota, 2004 Mesoscale Discussions in Iowa, 2004 Every mesoscale discussion in 2004

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.